Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_prot.c
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1 /* 2 * Copyright (c) 1982, 1986, 1989, 1990, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * Copyright (c) 2000-2001 Robert N. M. Watson. All rights reserved. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * @(#)kern_prot.c 8.6 (Berkeley) 1/21/94 36 */ 37 38 /* 39 * System calls related to processes and protection 40 */ 41 42 #include <sys/cdefs.h> 43 __FBSDID("$FreeBSD: releng/5.3/sys/kern/kern_prot.c 136588 2004-10-16 08:43:07Z cvs2svn $"); 44 45 #include "opt_compat.h" 46 #include "opt_mac.h" 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/acct.h> 51 #include <sys/kdb.h> 52 #include <sys/kernel.h> 53 #include <sys/lock.h> 54 #include <sys/mac.h> 55 #include <sys/malloc.h> 56 #include <sys/mutex.h> 57 #include <sys/sx.h> 58 #include <sys/proc.h> 59 #include <sys/sysproto.h> 60 #include <sys/jail.h> 61 #include <sys/pioctl.h> 62 #include <sys/resourcevar.h> 63 #include <sys/socket.h> 64 #include <sys/socketvar.h> 65 #include <sys/sysctl.h> 66 67 static MALLOC_DEFINE(M_CRED, "cred", "credentials"); 68 69 SYSCTL_DECL(_security); 70 SYSCTL_NODE(_security, OID_AUTO, bsd, CTLFLAG_RW, 0, 71 "BSD security policy"); 72 73 #ifndef _SYS_SYSPROTO_H_ 74 struct getpid_args { 75 int dummy; 76 }; 77 #endif 78 /* 79 * MPSAFE 80 */ 81 /* ARGSUSED */ 82 int 83 getpid(struct thread *td, struct getpid_args *uap) 84 { 85 struct proc *p = td->td_proc; 86 87 td->td_retval[0] = p->p_pid; 88 #if defined(COMPAT_43) 89 PROC_LOCK(p); 90 td->td_retval[1] = p->p_pptr->p_pid; 91 PROC_UNLOCK(p); 92 #endif 93 return (0); 94 } 95 96 #ifndef _SYS_SYSPROTO_H_ 97 struct getppid_args { 98 int dummy; 99 }; 100 #endif 101 /* 102 * MPSAFE 103 */ 104 /* ARGSUSED */ 105 int 106 getppid(struct thread *td, struct getppid_args *uap) 107 { 108 struct proc *p = td->td_proc; 109 110 PROC_LOCK(p); 111 td->td_retval[0] = p->p_pptr->p_pid; 112 PROC_UNLOCK(p); 113 return (0); 114 } 115 116 /* 117 * Get process group ID; note that POSIX getpgrp takes no parameter. 118 */ 119 #ifndef _SYS_SYSPROTO_H_ 120 struct getpgrp_args { 121 int dummy; 122 }; 123 #endif 124 /* 125 * MPSAFE 126 */ 127 int 128 getpgrp(struct thread *td, struct getpgrp_args *uap) 129 { 130 struct proc *p = td->td_proc; 131 132 PROC_LOCK(p); 133 td->td_retval[0] = p->p_pgrp->pg_id; 134 PROC_UNLOCK(p); 135 return (0); 136 } 137 138 /* Get an arbitary pid's process group id */ 139 #ifndef _SYS_SYSPROTO_H_ 140 struct getpgid_args { 141 pid_t pid; 142 }; 143 #endif 144 /* 145 * MPSAFE 146 */ 147 int 148 getpgid(struct thread *td, struct getpgid_args *uap) 149 { 150 struct proc *p; 151 int error; 152 153 if (uap->pid == 0) { 154 p = td->td_proc; 155 PROC_LOCK(p); 156 } else { 157 p = pfind(uap->pid); 158 if (p == NULL) 159 return (ESRCH); 160 error = p_cansee(td, p); 161 if (error) { 162 PROC_UNLOCK(p); 163 return (error); 164 } 165 } 166 td->td_retval[0] = p->p_pgrp->pg_id; 167 PROC_UNLOCK(p); 168 return (0); 169 } 170 171 /* 172 * Get an arbitary pid's session id. 173 */ 174 #ifndef _SYS_SYSPROTO_H_ 175 struct getsid_args { 176 pid_t pid; 177 }; 178 #endif 179 /* 180 * MPSAFE 181 */ 182 int 183 getsid(struct thread *td, struct getsid_args *uap) 184 { 185 struct proc *p; 186 int error; 187 188 if (uap->pid == 0) { 189 p = td->td_proc; 190 PROC_LOCK(p); 191 } else { 192 p = pfind(uap->pid); 193 if (p == NULL) 194 return (ESRCH); 195 error = p_cansee(td, p); 196 if (error) { 197 PROC_UNLOCK(p); 198 return (error); 199 } 200 } 201 td->td_retval[0] = p->p_session->s_sid; 202 PROC_UNLOCK(p); 203 return (0); 204 } 205 206 #ifndef _SYS_SYSPROTO_H_ 207 struct getuid_args { 208 int dummy; 209 }; 210 #endif 211 /* 212 * MPSAFE 213 */ 214 /* ARGSUSED */ 215 int 216 getuid(struct thread *td, struct getuid_args *uap) 217 { 218 219 td->td_retval[0] = td->td_ucred->cr_ruid; 220 #if defined(COMPAT_43) 221 td->td_retval[1] = td->td_ucred->cr_uid; 222 #endif 223 return (0); 224 } 225 226 #ifndef _SYS_SYSPROTO_H_ 227 struct geteuid_args { 228 int dummy; 229 }; 230 #endif 231 /* 232 * MPSAFE 233 */ 234 /* ARGSUSED */ 235 int 236 geteuid(struct thread *td, struct geteuid_args *uap) 237 { 238 239 td->td_retval[0] = td->td_ucred->cr_uid; 240 return (0); 241 } 242 243 #ifndef _SYS_SYSPROTO_H_ 244 struct getgid_args { 245 int dummy; 246 }; 247 #endif 248 /* 249 * MPSAFE 250 */ 251 /* ARGSUSED */ 252 int 253 getgid(struct thread *td, struct getgid_args *uap) 254 { 255 256 td->td_retval[0] = td->td_ucred->cr_rgid; 257 #if defined(COMPAT_43) 258 td->td_retval[1] = td->td_ucred->cr_groups[0]; 259 #endif 260 return (0); 261 } 262 263 /* 264 * Get effective group ID. The "egid" is groups[0], and could be obtained 265 * via getgroups. This syscall exists because it is somewhat painful to do 266 * correctly in a library function. 267 */ 268 #ifndef _SYS_SYSPROTO_H_ 269 struct getegid_args { 270 int dummy; 271 }; 272 #endif 273 /* 274 * MPSAFE 275 */ 276 /* ARGSUSED */ 277 int 278 getegid(struct thread *td, struct getegid_args *uap) 279 { 280 281 td->td_retval[0] = td->td_ucred->cr_groups[0]; 282 return (0); 283 } 284 285 #ifndef _SYS_SYSPROTO_H_ 286 struct getgroups_args { 287 u_int gidsetsize; 288 gid_t *gidset; 289 }; 290 #endif 291 /* 292 * MPSAFE 293 */ 294 int 295 getgroups(struct thread *td, register struct getgroups_args *uap) 296 { 297 struct ucred *cred; 298 u_int ngrp; 299 int error; 300 301 cred = td->td_ucred; 302 if ((ngrp = uap->gidsetsize) == 0) { 303 td->td_retval[0] = cred->cr_ngroups; 304 return (0); 305 } 306 if (ngrp < cred->cr_ngroups) 307 return (EINVAL); 308 ngrp = cred->cr_ngroups; 309 error = copyout(cred->cr_groups, uap->gidset, ngrp * sizeof(gid_t)); 310 if (error == 0) 311 td->td_retval[0] = ngrp; 312 return (error); 313 } 314 315 #ifndef _SYS_SYSPROTO_H_ 316 struct setsid_args { 317 int dummy; 318 }; 319 #endif 320 /* 321 * MPSAFE 322 */ 323 /* ARGSUSED */ 324 int 325 setsid(register struct thread *td, struct setsid_args *uap) 326 { 327 struct pgrp *pgrp; 328 int error; 329 struct proc *p = td->td_proc; 330 struct pgrp *newpgrp; 331 struct session *newsess; 332 333 error = 0; 334 pgrp = NULL; 335 336 MALLOC(newpgrp, struct pgrp *, sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO); 337 MALLOC(newsess, struct session *, sizeof(struct session), M_SESSION, M_WAITOK | M_ZERO); 338 339 sx_xlock(&proctree_lock); 340 341 if (p->p_pgid == p->p_pid || (pgrp = pgfind(p->p_pid)) != NULL) { 342 if (pgrp != NULL) 343 PGRP_UNLOCK(pgrp); 344 error = EPERM; 345 } else { 346 (void)enterpgrp(p, p->p_pid, newpgrp, newsess); 347 td->td_retval[0] = p->p_pid; 348 newpgrp = NULL; 349 newsess = NULL; 350 } 351 352 sx_xunlock(&proctree_lock); 353 354 if (newpgrp != NULL) 355 FREE(newpgrp, M_PGRP); 356 if (newsess != NULL) 357 FREE(newsess, M_SESSION); 358 359 return (error); 360 } 361 362 /* 363 * set process group (setpgid/old setpgrp) 364 * 365 * caller does setpgid(targpid, targpgid) 366 * 367 * pid must be caller or child of caller (ESRCH) 368 * if a child 369 * pid must be in same session (EPERM) 370 * pid can't have done an exec (EACCES) 371 * if pgid != pid 372 * there must exist some pid in same session having pgid (EPERM) 373 * pid must not be session leader (EPERM) 374 */ 375 #ifndef _SYS_SYSPROTO_H_ 376 struct setpgid_args { 377 int pid; /* target process id */ 378 int pgid; /* target pgrp id */ 379 }; 380 #endif 381 /* 382 * MPSAFE 383 */ 384 /* ARGSUSED */ 385 int 386 setpgid(struct thread *td, register struct setpgid_args *uap) 387 { 388 struct proc *curp = td->td_proc; 389 register struct proc *targp; /* target process */ 390 register struct pgrp *pgrp; /* target pgrp */ 391 int error; 392 struct pgrp *newpgrp; 393 394 if (uap->pgid < 0) 395 return (EINVAL); 396 397 error = 0; 398 399 MALLOC(newpgrp, struct pgrp *, sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO); 400 401 sx_xlock(&proctree_lock); 402 if (uap->pid != 0 && uap->pid != curp->p_pid) { 403 if ((targp = pfind(uap->pid)) == NULL) { 404 error = ESRCH; 405 goto done; 406 } 407 if (!inferior(targp)) { 408 PROC_UNLOCK(targp); 409 error = ESRCH; 410 goto done; 411 } 412 if ((error = p_cansee(td, targp))) { 413 PROC_UNLOCK(targp); 414 goto done; 415 } 416 if (targp->p_pgrp == NULL || 417 targp->p_session != curp->p_session) { 418 PROC_UNLOCK(targp); 419 error = EPERM; 420 goto done; 421 } 422 if (targp->p_flag & P_EXEC) { 423 PROC_UNLOCK(targp); 424 error = EACCES; 425 goto done; 426 } 427 PROC_UNLOCK(targp); 428 } else 429 targp = curp; 430 if (SESS_LEADER(targp)) { 431 error = EPERM; 432 goto done; 433 } 434 if (uap->pgid == 0) 435 uap->pgid = targp->p_pid; 436 if ((pgrp = pgfind(uap->pgid)) == NULL) { 437 if (uap->pgid == targp->p_pid) { 438 error = enterpgrp(targp, uap->pgid, newpgrp, 439 NULL); 440 if (error == 0) 441 newpgrp = NULL; 442 } else 443 error = EPERM; 444 } else { 445 if (pgrp == targp->p_pgrp) { 446 PGRP_UNLOCK(pgrp); 447 goto done; 448 } 449 if (pgrp->pg_id != targp->p_pid && 450 pgrp->pg_session != curp->p_session) { 451 PGRP_UNLOCK(pgrp); 452 error = EPERM; 453 goto done; 454 } 455 PGRP_UNLOCK(pgrp); 456 error = enterthispgrp(targp, pgrp); 457 } 458 done: 459 sx_xunlock(&proctree_lock); 460 KASSERT((error == 0) || (newpgrp != NULL), 461 ("setpgid failed and newpgrp is NULL")); 462 if (newpgrp != NULL) 463 FREE(newpgrp, M_PGRP); 464 return (error); 465 } 466 467 /* 468 * Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD 469 * compatible. It says that setting the uid/gid to euid/egid is a special 470 * case of "appropriate privilege". Once the rules are expanded out, this 471 * basically means that setuid(nnn) sets all three id's, in all permitted 472 * cases unless _POSIX_SAVED_IDS is enabled. In that case, setuid(getuid()) 473 * does not set the saved id - this is dangerous for traditional BSD 474 * programs. For this reason, we *really* do not want to set 475 * _POSIX_SAVED_IDS and do not want to clear POSIX_APPENDIX_B_4_2_2. 476 */ 477 #define POSIX_APPENDIX_B_4_2_2 478 479 #ifndef _SYS_SYSPROTO_H_ 480 struct setuid_args { 481 uid_t uid; 482 }; 483 #endif 484 /* 485 * MPSAFE 486 */ 487 /* ARGSUSED */ 488 int 489 setuid(struct thread *td, struct setuid_args *uap) 490 { 491 struct proc *p = td->td_proc; 492 struct ucred *newcred, *oldcred; 493 uid_t uid; 494 struct uidinfo *uip; 495 int error; 496 497 uid = uap->uid; 498 newcred = crget(); 499 uip = uifind(uid); 500 PROC_LOCK(p); 501 oldcred = p->p_ucred; 502 503 /* 504 * See if we have "permission" by POSIX 1003.1 rules. 505 * 506 * Note that setuid(geteuid()) is a special case of 507 * "appropriate privileges" in appendix B.4.2.2. We need 508 * to use this clause to be compatible with traditional BSD 509 * semantics. Basically, it means that "setuid(xx)" sets all 510 * three id's (assuming you have privs). 511 * 512 * Notes on the logic. We do things in three steps. 513 * 1: We determine if the euid is going to change, and do EPERM 514 * right away. We unconditionally change the euid later if this 515 * test is satisfied, simplifying that part of the logic. 516 * 2: We determine if the real and/or saved uids are going to 517 * change. Determined by compile options. 518 * 3: Change euid last. (after tests in #2 for "appropriate privs") 519 */ 520 if (uid != oldcred->cr_ruid && /* allow setuid(getuid()) */ 521 #ifdef _POSIX_SAVED_IDS 522 uid != oldcred->cr_svuid && /* allow setuid(saved gid) */ 523 #endif 524 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 525 uid != oldcred->cr_uid && /* allow setuid(geteuid()) */ 526 #endif 527 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 528 PROC_UNLOCK(p); 529 uifree(uip); 530 crfree(newcred); 531 return (error); 532 } 533 534 /* 535 * Copy credentials so other references do not see our changes. 536 */ 537 crcopy(newcred, oldcred); 538 #ifdef _POSIX_SAVED_IDS 539 /* 540 * Do we have "appropriate privileges" (are we root or uid == euid) 541 * If so, we are changing the real uid and/or saved uid. 542 */ 543 if ( 544 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use the clause from B.4.2.2 */ 545 uid == oldcred->cr_uid || 546 #endif 547 suser_cred(oldcred, SUSER_ALLOWJAIL) == 0) /* we are using privs */ 548 #endif 549 { 550 /* 551 * Set the real uid and transfer proc count to new user. 552 */ 553 if (uid != oldcred->cr_ruid) { 554 change_ruid(newcred, uip); 555 setsugid(p); 556 } 557 /* 558 * Set saved uid 559 * 560 * XXX always set saved uid even if not _POSIX_SAVED_IDS, as 561 * the security of seteuid() depends on it. B.4.2.2 says it 562 * is important that we should do this. 563 */ 564 if (uid != oldcred->cr_svuid) { 565 change_svuid(newcred, uid); 566 setsugid(p); 567 } 568 } 569 570 /* 571 * In all permitted cases, we are changing the euid. 572 */ 573 if (uid != oldcred->cr_uid) { 574 change_euid(newcred, uip); 575 setsugid(p); 576 } 577 p->p_ucred = newcred; 578 PROC_UNLOCK(p); 579 uifree(uip); 580 crfree(oldcred); 581 return (0); 582 } 583 584 #ifndef _SYS_SYSPROTO_H_ 585 struct seteuid_args { 586 uid_t euid; 587 }; 588 #endif 589 /* 590 * MPSAFE 591 */ 592 /* ARGSUSED */ 593 int 594 seteuid(struct thread *td, struct seteuid_args *uap) 595 { 596 struct proc *p = td->td_proc; 597 struct ucred *newcred, *oldcred; 598 uid_t euid; 599 struct uidinfo *euip; 600 int error; 601 602 euid = uap->euid; 603 newcred = crget(); 604 euip = uifind(euid); 605 PROC_LOCK(p); 606 oldcred = p->p_ucred; 607 if (euid != oldcred->cr_ruid && /* allow seteuid(getuid()) */ 608 euid != oldcred->cr_svuid && /* allow seteuid(saved uid) */ 609 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 610 PROC_UNLOCK(p); 611 uifree(euip); 612 crfree(newcred); 613 return (error); 614 } 615 /* 616 * Everything's okay, do it. Copy credentials so other references do 617 * not see our changes. 618 */ 619 crcopy(newcred, oldcred); 620 if (oldcred->cr_uid != euid) { 621 change_euid(newcred, euip); 622 setsugid(p); 623 } 624 p->p_ucred = newcred; 625 PROC_UNLOCK(p); 626 uifree(euip); 627 crfree(oldcred); 628 return (0); 629 } 630 631 #ifndef _SYS_SYSPROTO_H_ 632 struct setgid_args { 633 gid_t gid; 634 }; 635 #endif 636 /* 637 * MPSAFE 638 */ 639 /* ARGSUSED */ 640 int 641 setgid(struct thread *td, struct setgid_args *uap) 642 { 643 struct proc *p = td->td_proc; 644 struct ucred *newcred, *oldcred; 645 gid_t gid; 646 int error; 647 648 gid = uap->gid; 649 newcred = crget(); 650 PROC_LOCK(p); 651 oldcred = p->p_ucred; 652 653 /* 654 * See if we have "permission" by POSIX 1003.1 rules. 655 * 656 * Note that setgid(getegid()) is a special case of 657 * "appropriate privileges" in appendix B.4.2.2. We need 658 * to use this clause to be compatible with traditional BSD 659 * semantics. Basically, it means that "setgid(xx)" sets all 660 * three id's (assuming you have privs). 661 * 662 * For notes on the logic here, see setuid() above. 663 */ 664 if (gid != oldcred->cr_rgid && /* allow setgid(getgid()) */ 665 #ifdef _POSIX_SAVED_IDS 666 gid != oldcred->cr_svgid && /* allow setgid(saved gid) */ 667 #endif 668 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 669 gid != oldcred->cr_groups[0] && /* allow setgid(getegid()) */ 670 #endif 671 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 672 PROC_UNLOCK(p); 673 crfree(newcred); 674 return (error); 675 } 676 677 crcopy(newcred, oldcred); 678 #ifdef _POSIX_SAVED_IDS 679 /* 680 * Do we have "appropriate privileges" (are we root or gid == egid) 681 * If so, we are changing the real uid and saved gid. 682 */ 683 if ( 684 #ifdef POSIX_APPENDIX_B_4_2_2 /* use the clause from B.4.2.2 */ 685 gid == oldcred->cr_groups[0] || 686 #endif 687 suser_cred(oldcred, SUSER_ALLOWJAIL) == 0) /* we are using privs */ 688 #endif 689 { 690 /* 691 * Set real gid 692 */ 693 if (oldcred->cr_rgid != gid) { 694 change_rgid(newcred, gid); 695 setsugid(p); 696 } 697 /* 698 * Set saved gid 699 * 700 * XXX always set saved gid even if not _POSIX_SAVED_IDS, as 701 * the security of setegid() depends on it. B.4.2.2 says it 702 * is important that we should do this. 703 */ 704 if (oldcred->cr_svgid != gid) { 705 change_svgid(newcred, gid); 706 setsugid(p); 707 } 708 } 709 /* 710 * In all cases permitted cases, we are changing the egid. 711 * Copy credentials so other references do not see our changes. 712 */ 713 if (oldcred->cr_groups[0] != gid) { 714 change_egid(newcred, gid); 715 setsugid(p); 716 } 717 p->p_ucred = newcred; 718 PROC_UNLOCK(p); 719 crfree(oldcred); 720 return (0); 721 } 722 723 #ifndef _SYS_SYSPROTO_H_ 724 struct setegid_args { 725 gid_t egid; 726 }; 727 #endif 728 /* 729 * MPSAFE 730 */ 731 /* ARGSUSED */ 732 int 733 setegid(struct thread *td, struct setegid_args *uap) 734 { 735 struct proc *p = td->td_proc; 736 struct ucred *newcred, *oldcred; 737 gid_t egid; 738 int error; 739 740 egid = uap->egid; 741 newcred = crget(); 742 PROC_LOCK(p); 743 oldcred = p->p_ucred; 744 if (egid != oldcred->cr_rgid && /* allow setegid(getgid()) */ 745 egid != oldcred->cr_svgid && /* allow setegid(saved gid) */ 746 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 747 PROC_UNLOCK(p); 748 crfree(newcred); 749 return (error); 750 } 751 crcopy(newcred, oldcred); 752 if (oldcred->cr_groups[0] != egid) { 753 change_egid(newcred, egid); 754 setsugid(p); 755 } 756 p->p_ucred = newcred; 757 PROC_UNLOCK(p); 758 crfree(oldcred); 759 return (0); 760 } 761 762 #ifndef _SYS_SYSPROTO_H_ 763 struct setgroups_args { 764 u_int gidsetsize; 765 gid_t *gidset; 766 }; 767 #endif 768 /* 769 * MPSAFE 770 */ 771 /* ARGSUSED */ 772 int 773 setgroups(struct thread *td, struct setgroups_args *uap) 774 { 775 struct proc *p = td->td_proc; 776 struct ucred *newcred, *tempcred, *oldcred; 777 u_int ngrp; 778 int error; 779 780 ngrp = uap->gidsetsize; 781 if (ngrp > NGROUPS) 782 return (EINVAL); 783 tempcred = crget(); 784 error = copyin(uap->gidset, tempcred->cr_groups, ngrp * sizeof(gid_t)); 785 if (error != 0) { 786 crfree(tempcred); 787 return (error); 788 } 789 newcred = crget(); 790 PROC_LOCK(p); 791 oldcred = p->p_ucred; 792 error = suser_cred(oldcred, SUSER_ALLOWJAIL); 793 if (error) { 794 PROC_UNLOCK(p); 795 crfree(newcred); 796 crfree(tempcred); 797 return (error); 798 } 799 800 /* 801 * XXX A little bit lazy here. We could test if anything has 802 * changed before crcopy() and setting P_SUGID. 803 */ 804 crcopy(newcred, oldcred); 805 if (ngrp < 1) { 806 /* 807 * setgroups(0, NULL) is a legitimate way of clearing the 808 * groups vector on non-BSD systems (which generally do not 809 * have the egid in the groups[0]). We risk security holes 810 * when running non-BSD software if we do not do the same. 811 */ 812 newcred->cr_ngroups = 1; 813 } else { 814 bcopy(tempcred->cr_groups, newcred->cr_groups, 815 ngrp * sizeof(gid_t)); 816 newcred->cr_ngroups = ngrp; 817 } 818 setsugid(p); 819 p->p_ucred = newcred; 820 PROC_UNLOCK(p); 821 crfree(tempcred); 822 crfree(oldcred); 823 return (0); 824 } 825 826 #ifndef _SYS_SYSPROTO_H_ 827 struct setreuid_args { 828 uid_t ruid; 829 uid_t euid; 830 }; 831 #endif 832 /* 833 * MPSAFE 834 */ 835 /* ARGSUSED */ 836 int 837 setreuid(register struct thread *td, struct setreuid_args *uap) 838 { 839 struct proc *p = td->td_proc; 840 struct ucred *newcred, *oldcred; 841 uid_t euid, ruid; 842 struct uidinfo *euip, *ruip; 843 int error; 844 845 euid = uap->euid; 846 ruid = uap->ruid; 847 newcred = crget(); 848 euip = uifind(euid); 849 ruip = uifind(ruid); 850 PROC_LOCK(p); 851 oldcred = p->p_ucred; 852 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && 853 ruid != oldcred->cr_svuid) || 854 (euid != (uid_t)-1 && euid != oldcred->cr_uid && 855 euid != oldcred->cr_ruid && euid != oldcred->cr_svuid)) && 856 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 857 PROC_UNLOCK(p); 858 uifree(ruip); 859 uifree(euip); 860 crfree(newcred); 861 return (error); 862 } 863 crcopy(newcred, oldcred); 864 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { 865 change_euid(newcred, euip); 866 setsugid(p); 867 } 868 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { 869 change_ruid(newcred, ruip); 870 setsugid(p); 871 } 872 if ((ruid != (uid_t)-1 || newcred->cr_uid != newcred->cr_ruid) && 873 newcred->cr_svuid != newcred->cr_uid) { 874 change_svuid(newcred, newcred->cr_uid); 875 setsugid(p); 876 } 877 p->p_ucred = newcred; 878 PROC_UNLOCK(p); 879 uifree(ruip); 880 uifree(euip); 881 crfree(oldcred); 882 return (0); 883 } 884 885 #ifndef _SYS_SYSPROTO_H_ 886 struct setregid_args { 887 gid_t rgid; 888 gid_t egid; 889 }; 890 #endif 891 /* 892 * MPSAFE 893 */ 894 /* ARGSUSED */ 895 int 896 setregid(register struct thread *td, struct setregid_args *uap) 897 { 898 struct proc *p = td->td_proc; 899 struct ucred *newcred, *oldcred; 900 gid_t egid, rgid; 901 int error; 902 903 egid = uap->egid; 904 rgid = uap->rgid; 905 newcred = crget(); 906 PROC_LOCK(p); 907 oldcred = p->p_ucred; 908 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && 909 rgid != oldcred->cr_svgid) || 910 (egid != (gid_t)-1 && egid != oldcred->cr_groups[0] && 911 egid != oldcred->cr_rgid && egid != oldcred->cr_svgid)) && 912 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 913 PROC_UNLOCK(p); 914 crfree(newcred); 915 return (error); 916 } 917 918 crcopy(newcred, oldcred); 919 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { 920 change_egid(newcred, egid); 921 setsugid(p); 922 } 923 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { 924 change_rgid(newcred, rgid); 925 setsugid(p); 926 } 927 if ((rgid != (gid_t)-1 || newcred->cr_groups[0] != newcred->cr_rgid) && 928 newcred->cr_svgid != newcred->cr_groups[0]) { 929 change_svgid(newcred, newcred->cr_groups[0]); 930 setsugid(p); 931 } 932 p->p_ucred = newcred; 933 PROC_UNLOCK(p); 934 crfree(oldcred); 935 return (0); 936 } 937 938 /* 939 * setresuid(ruid, euid, suid) is like setreuid except control over the 940 * saved uid is explicit. 941 */ 942 943 #ifndef _SYS_SYSPROTO_H_ 944 struct setresuid_args { 945 uid_t ruid; 946 uid_t euid; 947 uid_t suid; 948 }; 949 #endif 950 /* 951 * MPSAFE 952 */ 953 /* ARGSUSED */ 954 int 955 setresuid(register struct thread *td, struct setresuid_args *uap) 956 { 957 struct proc *p = td->td_proc; 958 struct ucred *newcred, *oldcred; 959 uid_t euid, ruid, suid; 960 struct uidinfo *euip, *ruip; 961 int error; 962 963 euid = uap->euid; 964 ruid = uap->ruid; 965 suid = uap->suid; 966 newcred = crget(); 967 euip = uifind(euid); 968 ruip = uifind(ruid); 969 PROC_LOCK(p); 970 oldcred = p->p_ucred; 971 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && 972 ruid != oldcred->cr_svuid && 973 ruid != oldcred->cr_uid) || 974 (euid != (uid_t)-1 && euid != oldcred->cr_ruid && 975 euid != oldcred->cr_svuid && 976 euid != oldcred->cr_uid) || 977 (suid != (uid_t)-1 && suid != oldcred->cr_ruid && 978 suid != oldcred->cr_svuid && 979 suid != oldcred->cr_uid)) && 980 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 981 PROC_UNLOCK(p); 982 uifree(ruip); 983 uifree(euip); 984 crfree(newcred); 985 return (error); 986 } 987 988 crcopy(newcred, oldcred); 989 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { 990 change_euid(newcred, euip); 991 setsugid(p); 992 } 993 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { 994 change_ruid(newcred, ruip); 995 setsugid(p); 996 } 997 if (suid != (uid_t)-1 && oldcred->cr_svuid != suid) { 998 change_svuid(newcred, suid); 999 setsugid(p); 1000 } 1001 p->p_ucred = newcred; 1002 PROC_UNLOCK(p); 1003 uifree(ruip); 1004 uifree(euip); 1005 crfree(oldcred); 1006 return (0); 1007 } 1008 1009 /* 1010 * setresgid(rgid, egid, sgid) is like setregid except control over the 1011 * saved gid is explicit. 1012 */ 1013 1014 #ifndef _SYS_SYSPROTO_H_ 1015 struct setresgid_args { 1016 gid_t rgid; 1017 gid_t egid; 1018 gid_t sgid; 1019 }; 1020 #endif 1021 /* 1022 * MPSAFE 1023 */ 1024 /* ARGSUSED */ 1025 int 1026 setresgid(register struct thread *td, struct setresgid_args *uap) 1027 { 1028 struct proc *p = td->td_proc; 1029 struct ucred *newcred, *oldcred; 1030 gid_t egid, rgid, sgid; 1031 int error; 1032 1033 egid = uap->egid; 1034 rgid = uap->rgid; 1035 sgid = uap->sgid; 1036 newcred = crget(); 1037 PROC_LOCK(p); 1038 oldcred = p->p_ucred; 1039 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && 1040 rgid != oldcred->cr_svgid && 1041 rgid != oldcred->cr_groups[0]) || 1042 (egid != (gid_t)-1 && egid != oldcred->cr_rgid && 1043 egid != oldcred->cr_svgid && 1044 egid != oldcred->cr_groups[0]) || 1045 (sgid != (gid_t)-1 && sgid != oldcred->cr_rgid && 1046 sgid != oldcred->cr_svgid && 1047 sgid != oldcred->cr_groups[0])) && 1048 (error = suser_cred(oldcred, SUSER_ALLOWJAIL)) != 0) { 1049 PROC_UNLOCK(p); 1050 crfree(newcred); 1051 return (error); 1052 } 1053 1054 crcopy(newcred, oldcred); 1055 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { 1056 change_egid(newcred, egid); 1057 setsugid(p); 1058 } 1059 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { 1060 change_rgid(newcred, rgid); 1061 setsugid(p); 1062 } 1063 if (sgid != (gid_t)-1 && oldcred->cr_svgid != sgid) { 1064 change_svgid(newcred, sgid); 1065 setsugid(p); 1066 } 1067 p->p_ucred = newcred; 1068 PROC_UNLOCK(p); 1069 crfree(oldcred); 1070 return (0); 1071 } 1072 1073 #ifndef _SYS_SYSPROTO_H_ 1074 struct getresuid_args { 1075 uid_t *ruid; 1076 uid_t *euid; 1077 uid_t *suid; 1078 }; 1079 #endif 1080 /* 1081 * MPSAFE 1082 */ 1083 /* ARGSUSED */ 1084 int 1085 getresuid(register struct thread *td, struct getresuid_args *uap) 1086 { 1087 struct ucred *cred; 1088 int error1 = 0, error2 = 0, error3 = 0; 1089 1090 cred = td->td_ucred; 1091 if (uap->ruid) 1092 error1 = copyout(&cred->cr_ruid, 1093 uap->ruid, sizeof(cred->cr_ruid)); 1094 if (uap->euid) 1095 error2 = copyout(&cred->cr_uid, 1096 uap->euid, sizeof(cred->cr_uid)); 1097 if (uap->suid) 1098 error3 = copyout(&cred->cr_svuid, 1099 uap->suid, sizeof(cred->cr_svuid)); 1100 return (error1 ? error1 : error2 ? error2 : error3); 1101 } 1102 1103 #ifndef _SYS_SYSPROTO_H_ 1104 struct getresgid_args { 1105 gid_t *rgid; 1106 gid_t *egid; 1107 gid_t *sgid; 1108 }; 1109 #endif 1110 /* 1111 * MPSAFE 1112 */ 1113 /* ARGSUSED */ 1114 int 1115 getresgid(register struct thread *td, struct getresgid_args *uap) 1116 { 1117 struct ucred *cred; 1118 int error1 = 0, error2 = 0, error3 = 0; 1119 1120 cred = td->td_ucred; 1121 if (uap->rgid) 1122 error1 = copyout(&cred->cr_rgid, 1123 uap->rgid, sizeof(cred->cr_rgid)); 1124 if (uap->egid) 1125 error2 = copyout(&cred->cr_groups[0], 1126 uap->egid, sizeof(cred->cr_groups[0])); 1127 if (uap->sgid) 1128 error3 = copyout(&cred->cr_svgid, 1129 uap->sgid, sizeof(cred->cr_svgid)); 1130 return (error1 ? error1 : error2 ? error2 : error3); 1131 } 1132 1133 #ifndef _SYS_SYSPROTO_H_ 1134 struct issetugid_args { 1135 int dummy; 1136 }; 1137 #endif 1138 /* 1139 * MPSAFE 1140 */ 1141 /* ARGSUSED */ 1142 int 1143 issetugid(register struct thread *td, struct issetugid_args *uap) 1144 { 1145 struct proc *p = td->td_proc; 1146 1147 /* 1148 * Note: OpenBSD sets a P_SUGIDEXEC flag set at execve() time, 1149 * we use P_SUGID because we consider changing the owners as 1150 * "tainting" as well. 1151 * This is significant for procs that start as root and "become" 1152 * a user without an exec - programs cannot know *everything* 1153 * that libc *might* have put in their data segment. 1154 */ 1155 PROC_LOCK(p); 1156 td->td_retval[0] = (p->p_flag & P_SUGID) ? 1 : 0; 1157 PROC_UNLOCK(p); 1158 return (0); 1159 } 1160 1161 /* 1162 * MPSAFE 1163 */ 1164 int 1165 __setugid(struct thread *td, struct __setugid_args *uap) 1166 { 1167 #ifdef REGRESSION 1168 struct proc *p; 1169 1170 p = td->td_proc; 1171 switch (uap->flag) { 1172 case 0: 1173 PROC_LOCK(p); 1174 p->p_flag &= ~P_SUGID; 1175 PROC_UNLOCK(p); 1176 return (0); 1177 case 1: 1178 PROC_LOCK(p); 1179 p->p_flag |= P_SUGID; 1180 PROC_UNLOCK(p); 1181 return (0); 1182 default: 1183 return (EINVAL); 1184 } 1185 #else /* !REGRESSION */ 1186 1187 return (ENOSYS); 1188 #endif /* REGRESSION */ 1189 } 1190 1191 /* 1192 * Check if gid is a member of the group set. 1193 * 1194 * MPSAFE (cred must be held) 1195 */ 1196 int 1197 groupmember(gid_t gid, struct ucred *cred) 1198 { 1199 register gid_t *gp; 1200 gid_t *egp; 1201 1202 egp = &(cred->cr_groups[cred->cr_ngroups]); 1203 for (gp = cred->cr_groups; gp < egp; gp++) 1204 if (*gp == gid) 1205 return (1); 1206 return (0); 1207 } 1208 1209 /* 1210 * `suser_enabled' (which can be set by the security.suser_enabled 1211 * sysctl) determines whether the system 'super-user' policy is in effect. 1212 * If it is nonzero, an effective uid of 0 connotes special privilege, 1213 * overriding many mandatory and discretionary protections. If it is zero, 1214 * uid 0 is offered no special privilege in the kernel security policy. 1215 * Setting it to zero may seriously impact the functionality of many 1216 * existing userland programs, and should not be done without careful 1217 * consideration of the consequences. 1218 */ 1219 int suser_enabled = 1; 1220 SYSCTL_INT(_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW, 1221 &suser_enabled, 0, "processes with uid 0 have privilege"); 1222 TUNABLE_INT("security.bsd.suser_enabled", &suser_enabled); 1223 1224 /* 1225 * Test whether the specified credentials imply "super-user" privilege. 1226 * Return 0 or EPERM. 1227 */ 1228 int 1229 suser_cred(struct ucred *cred, int flag) 1230 { 1231 1232 if (!suser_enabled) 1233 return (EPERM); 1234 if (((flag & SUSER_RUID) ? cred->cr_ruid : cred->cr_uid) != 0) 1235 return (EPERM); 1236 if (jailed(cred) && !(flag & SUSER_ALLOWJAIL)) 1237 return (EPERM); 1238 return (0); 1239 } 1240 1241 /* 1242 * Shortcut to hide contents of struct td and struct proc from the 1243 * caller, promoting binary compatibility. 1244 */ 1245 int 1246 suser(struct thread *td) 1247 { 1248 1249 #ifdef INVARIANTS 1250 if (td != curthread) { 1251 printf("suser: thread %p (%d %s) != curthread %p (%d %s)\n", 1252 td, td->td_proc->p_pid, td->td_proc->p_comm, 1253 curthread, curthread->td_proc->p_pid, 1254 curthread->td_proc->p_comm); 1255 #ifdef KDB 1256 kdb_backtrace(); 1257 #endif 1258 } 1259 #endif 1260 return (suser_cred(td->td_ucred, 0)); 1261 } 1262 1263 /* 1264 * Test the active securelevel against a given level. securelevel_gt() 1265 * implements (securelevel > level). securelevel_ge() implements 1266 * (securelevel >= level). Note that the logic is inverted -- these 1267 * functions return EPERM on "success" and 0 on "failure". 1268 * 1269 * MPSAFE 1270 */ 1271 int 1272 securelevel_gt(struct ucred *cr, int level) 1273 { 1274 int active_securelevel; 1275 1276 active_securelevel = securelevel; 1277 KASSERT(cr != NULL, ("securelevel_gt: null cr")); 1278 if (cr->cr_prison != NULL) { 1279 mtx_lock(&cr->cr_prison->pr_mtx); 1280 active_securelevel = imax(cr->cr_prison->pr_securelevel, 1281 active_securelevel); 1282 mtx_unlock(&cr->cr_prison->pr_mtx); 1283 } 1284 return (active_securelevel > level ? EPERM : 0); 1285 } 1286 1287 int 1288 securelevel_ge(struct ucred *cr, int level) 1289 { 1290 int active_securelevel; 1291 1292 active_securelevel = securelevel; 1293 KASSERT(cr != NULL, ("securelevel_ge: null cr")); 1294 if (cr->cr_prison != NULL) { 1295 mtx_lock(&cr->cr_prison->pr_mtx); 1296 active_securelevel = imax(cr->cr_prison->pr_securelevel, 1297 active_securelevel); 1298 mtx_unlock(&cr->cr_prison->pr_mtx); 1299 } 1300 return (active_securelevel >= level ? EPERM : 0); 1301 } 1302 1303 /* 1304 * 'see_other_uids' determines whether or not visibility of processes 1305 * and sockets with credentials holding different real uids is possible 1306 * using a variety of system MIBs. 1307 * XXX: data declarations should be together near the beginning of the file. 1308 */ 1309 static int see_other_uids = 1; 1310 SYSCTL_INT(_security_bsd, OID_AUTO, see_other_uids, CTLFLAG_RW, 1311 &see_other_uids, 0, 1312 "Unprivileged processes may see subjects/objects with different real uid"); 1313 1314 /*- 1315 * Determine if u1 "can see" the subject specified by u2, according to the 1316 * 'see_other_uids' policy. 1317 * Returns: 0 for permitted, ESRCH otherwise 1318 * Locks: none 1319 * References: *u1 and *u2 must not change during the call 1320 * u1 may equal u2, in which case only one reference is required 1321 */ 1322 static int 1323 cr_seeotheruids(struct ucred *u1, struct ucred *u2) 1324 { 1325 1326 if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) { 1327 if (suser_cred(u1, SUSER_ALLOWJAIL) != 0) 1328 return (ESRCH); 1329 } 1330 return (0); 1331 } 1332 1333 /* 1334 * 'see_other_gids' determines whether or not visibility of processes 1335 * and sockets with credentials holding different real gids is possible 1336 * using a variety of system MIBs. 1337 * XXX: data declarations should be together near the beginning of the file. 1338 */ 1339 static int see_other_gids = 1; 1340 SYSCTL_INT(_security_bsd, OID_AUTO, see_other_gids, CTLFLAG_RW, 1341 &see_other_gids, 0, 1342 "Unprivileged processes may see subjects/objects with different real gid"); 1343 1344 /* 1345 * Determine if u1 can "see" the subject specified by u2, according to the 1346 * 'see_other_gids' policy. 1347 * Returns: 0 for permitted, ESRCH otherwise 1348 * Locks: none 1349 * References: *u1 and *u2 must not change during the call 1350 * u1 may equal u2, in which case only one reference is required 1351 */ 1352 static int 1353 cr_seeothergids(struct ucred *u1, struct ucred *u2) 1354 { 1355 int i, match; 1356 1357 if (!see_other_gids) { 1358 match = 0; 1359 for (i = 0; i < u1->cr_ngroups; i++) { 1360 if (groupmember(u1->cr_groups[i], u2)) 1361 match = 1; 1362 if (match) 1363 break; 1364 } 1365 if (!match) { 1366 if (suser_cred(u1, SUSER_ALLOWJAIL) != 0) 1367 return (ESRCH); 1368 } 1369 } 1370 return (0); 1371 } 1372 1373 /*- 1374 * Determine if u1 "can see" the subject specified by u2. 1375 * Returns: 0 for permitted, an errno value otherwise 1376 * Locks: none 1377 * References: *u1 and *u2 must not change during the call 1378 * u1 may equal u2, in which case only one reference is required 1379 */ 1380 int 1381 cr_cansee(struct ucred *u1, struct ucred *u2) 1382 { 1383 int error; 1384 1385 if ((error = prison_check(u1, u2))) 1386 return (error); 1387 #ifdef MAC 1388 if ((error = mac_check_cred_visible(u1, u2))) 1389 return (error); 1390 #endif 1391 if ((error = cr_seeotheruids(u1, u2))) 1392 return (error); 1393 if ((error = cr_seeothergids(u1, u2))) 1394 return (error); 1395 return (0); 1396 } 1397 1398 /*- 1399 * Determine if td "can see" the subject specified by p. 1400 * Returns: 0 for permitted, an errno value otherwise 1401 * Locks: Sufficient locks to protect p->p_ucred must be held. td really 1402 * should be curthread. 1403 * References: td and p must be valid for the lifetime of the call 1404 */ 1405 int 1406 p_cansee(struct thread *td, struct proc *p) 1407 { 1408 1409 /* Wrap cr_cansee() for all functionality. */ 1410 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1411 PROC_LOCK_ASSERT(p, MA_OWNED); 1412 return (cr_cansee(td->td_ucred, p->p_ucred)); 1413 } 1414 1415 /* 1416 * 'conservative_signals' prevents the delivery of a broad class of 1417 * signals by unprivileged processes to processes that have changed their 1418 * credentials since the last invocation of execve(). This can prevent 1419 * the leakage of cached information or retained privileges as a result 1420 * of a common class of signal-related vulnerabilities. However, this 1421 * may interfere with some applications that expect to be able to 1422 * deliver these signals to peer processes after having given up 1423 * privilege. 1424 */ 1425 static int conservative_signals = 1; 1426 SYSCTL_INT(_security_bsd, OID_AUTO, conservative_signals, CTLFLAG_RW, 1427 &conservative_signals, 0, "Unprivileged processes prevented from " 1428 "sending certain signals to processes whose credentials have changed"); 1429 /*- 1430 * Determine whether cred may deliver the specified signal to proc. 1431 * Returns: 0 for permitted, an errno value otherwise. 1432 * Locks: A lock must be held for proc. 1433 * References: cred and proc must be valid for the lifetime of the call. 1434 */ 1435 int 1436 cr_cansignal(struct ucred *cred, struct proc *proc, int signum) 1437 { 1438 int error; 1439 1440 PROC_LOCK_ASSERT(proc, MA_OWNED); 1441 /* 1442 * Jail semantics limit the scope of signalling to proc in the 1443 * same jail as cred, if cred is in jail. 1444 */ 1445 error = prison_check(cred, proc->p_ucred); 1446 if (error) 1447 return (error); 1448 #ifdef MAC 1449 if ((error = mac_check_proc_signal(cred, proc, signum))) 1450 return (error); 1451 #endif 1452 if ((error = cr_seeotheruids(cred, proc->p_ucred))) 1453 return (error); 1454 if ((error = cr_seeothergids(cred, proc->p_ucred))) 1455 return (error); 1456 1457 /* 1458 * UNIX signal semantics depend on the status of the P_SUGID 1459 * bit on the target process. If the bit is set, then additional 1460 * restrictions are placed on the set of available signals. 1461 */ 1462 if (conservative_signals && (proc->p_flag & P_SUGID)) { 1463 switch (signum) { 1464 case 0: 1465 case SIGKILL: 1466 case SIGINT: 1467 case SIGTERM: 1468 case SIGALRM: 1469 case SIGSTOP: 1470 case SIGTTIN: 1471 case SIGTTOU: 1472 case SIGTSTP: 1473 case SIGHUP: 1474 case SIGUSR1: 1475 case SIGUSR2: 1476 /* 1477 * Generally, permit job and terminal control 1478 * signals. 1479 */ 1480 break; 1481 default: 1482 /* Not permitted without privilege. */ 1483 error = suser_cred(cred, SUSER_ALLOWJAIL); 1484 if (error) 1485 return (error); 1486 } 1487 } 1488 1489 /* 1490 * Generally, the target credential's ruid or svuid must match the 1491 * subject credential's ruid or euid. 1492 */ 1493 if (cred->cr_ruid != proc->p_ucred->cr_ruid && 1494 cred->cr_ruid != proc->p_ucred->cr_svuid && 1495 cred->cr_uid != proc->p_ucred->cr_ruid && 1496 cred->cr_uid != proc->p_ucred->cr_svuid) { 1497 /* Not permitted without privilege. */ 1498 error = suser_cred(cred, SUSER_ALLOWJAIL); 1499 if (error) 1500 return (error); 1501 } 1502 1503 return (0); 1504 } 1505 1506 1507 /*- 1508 * Determine whether td may deliver the specified signal to p. 1509 * Returns: 0 for permitted, an errno value otherwise 1510 * Locks: Sufficient locks to protect various components of td and p 1511 * must be held. td must be curthread, and a lock must be 1512 * held for p. 1513 * References: td and p must be valid for the lifetime of the call 1514 */ 1515 int 1516 p_cansignal(struct thread *td, struct proc *p, int signum) 1517 { 1518 1519 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1520 PROC_LOCK_ASSERT(p, MA_OWNED); 1521 if (td->td_proc == p) 1522 return (0); 1523 1524 /* 1525 * UNIX signalling semantics require that processes in the same 1526 * session always be able to deliver SIGCONT to one another, 1527 * overriding the remaining protections. 1528 */ 1529 /* XXX: This will require an additional lock of some sort. */ 1530 if (signum == SIGCONT && td->td_proc->p_session == p->p_session) 1531 return (0); 1532 1533 return (cr_cansignal(td->td_ucred, p, signum)); 1534 } 1535 1536 /*- 1537 * Determine whether td may reschedule p. 1538 * Returns: 0 for permitted, an errno value otherwise 1539 * Locks: Sufficient locks to protect various components of td and p 1540 * must be held. td must be curthread, and a lock must 1541 * be held for p. 1542 * References: td and p must be valid for the lifetime of the call 1543 */ 1544 int 1545 p_cansched(struct thread *td, struct proc *p) 1546 { 1547 int error; 1548 1549 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1550 PROC_LOCK_ASSERT(p, MA_OWNED); 1551 if (td->td_proc == p) 1552 return (0); 1553 if ((error = prison_check(td->td_ucred, p->p_ucred))) 1554 return (error); 1555 #ifdef MAC 1556 if ((error = mac_check_proc_sched(td->td_ucred, p))) 1557 return (error); 1558 #endif 1559 if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred))) 1560 return (error); 1561 if ((error = cr_seeothergids(td->td_ucred, p->p_ucred))) 1562 return (error); 1563 if (td->td_ucred->cr_ruid == p->p_ucred->cr_ruid) 1564 return (0); 1565 if (td->td_ucred->cr_uid == p->p_ucred->cr_ruid) 1566 return (0); 1567 if (suser_cred(td->td_ucred, SUSER_ALLOWJAIL) == 0) 1568 return (0); 1569 1570 #ifdef CAPABILITIES 1571 if (!cap_check(NULL, td, CAP_SYS_NICE, SUSER_ALLOWJAIL)) 1572 return (0); 1573 #endif 1574 1575 return (EPERM); 1576 } 1577 1578 /* 1579 * The 'unprivileged_proc_debug' flag may be used to disable a variety of 1580 * unprivileged inter-process debugging services, including some procfs 1581 * functionality, ptrace(), and ktrace(). In the past, inter-process 1582 * debugging has been involved in a variety of security problems, and sites 1583 * not requiring the service might choose to disable it when hardening 1584 * systems. 1585 * 1586 * XXX: Should modifying and reading this variable require locking? 1587 * XXX: data declarations should be together near the beginning of the file. 1588 */ 1589 static int unprivileged_proc_debug = 1; 1590 SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_proc_debug, CTLFLAG_RW, 1591 &unprivileged_proc_debug, 0, 1592 "Unprivileged processes may use process debugging facilities"); 1593 1594 /*- 1595 * Determine whether td may debug p. 1596 * Returns: 0 for permitted, an errno value otherwise 1597 * Locks: Sufficient locks to protect various components of td and p 1598 * must be held. td must be curthread, and a lock must 1599 * be held for p. 1600 * References: td and p must be valid for the lifetime of the call 1601 */ 1602 int 1603 p_candebug(struct thread *td, struct proc *p) 1604 { 1605 int credentialchanged, error, grpsubset, i, uidsubset; 1606 1607 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1608 PROC_LOCK_ASSERT(p, MA_OWNED); 1609 if (!unprivileged_proc_debug) { 1610 error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL); 1611 if (error) 1612 return (error); 1613 } 1614 if (td->td_proc == p) 1615 return (0); 1616 if ((error = prison_check(td->td_ucred, p->p_ucred))) 1617 return (error); 1618 #ifdef MAC 1619 if ((error = mac_check_proc_debug(td->td_ucred, p))) 1620 return (error); 1621 #endif 1622 if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred))) 1623 return (error); 1624 if ((error = cr_seeothergids(td->td_ucred, p->p_ucred))) 1625 return (error); 1626 1627 /* 1628 * Is p's group set a subset of td's effective group set? This 1629 * includes p's egid, group access list, rgid, and svgid. 1630 */ 1631 grpsubset = 1; 1632 for (i = 0; i < p->p_ucred->cr_ngroups; i++) { 1633 if (!groupmember(p->p_ucred->cr_groups[i], td->td_ucred)) { 1634 grpsubset = 0; 1635 break; 1636 } 1637 } 1638 grpsubset = grpsubset && 1639 groupmember(p->p_ucred->cr_rgid, td->td_ucred) && 1640 groupmember(p->p_ucred->cr_svgid, td->td_ucred); 1641 1642 /* 1643 * Are the uids present in p's credential equal to td's 1644 * effective uid? This includes p's euid, svuid, and ruid. 1645 */ 1646 uidsubset = (td->td_ucred->cr_uid == p->p_ucred->cr_uid && 1647 td->td_ucred->cr_uid == p->p_ucred->cr_svuid && 1648 td->td_ucred->cr_uid == p->p_ucred->cr_ruid); 1649 1650 /* 1651 * Has the credential of the process changed since the last exec()? 1652 */ 1653 credentialchanged = (p->p_flag & P_SUGID); 1654 1655 /* 1656 * If p's gids aren't a subset, or the uids aren't a subset, 1657 * or the credential has changed, require appropriate privilege 1658 * for td to debug p. For POSIX.1e capabilities, this will 1659 * require CAP_SYS_PTRACE. 1660 */ 1661 if (!grpsubset || !uidsubset || credentialchanged) { 1662 error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL); 1663 if (error) 1664 return (error); 1665 } 1666 1667 /* Can't trace init when securelevel > 0. */ 1668 if (p == initproc) { 1669 error = securelevel_gt(td->td_ucred, 0); 1670 if (error) 1671 return (error); 1672 } 1673 1674 /* 1675 * Can't trace a process that's currently exec'ing. 1676 * XXX: Note, this is not a security policy decision, it's a 1677 * basic correctness/functionality decision. Therefore, this check 1678 * should be moved to the caller's of p_candebug(). 1679 */ 1680 if ((p->p_flag & P_INEXEC) != 0) 1681 return (EAGAIN); 1682 1683 return (0); 1684 } 1685 1686 /*- 1687 * Determine whether the subject represented by cred can "see" a socket. 1688 * Returns: 0 for permitted, ENOENT otherwise. 1689 */ 1690 int 1691 cr_canseesocket(struct ucred *cred, struct socket *so) 1692 { 1693 int error; 1694 1695 error = prison_check(cred, so->so_cred); 1696 if (error) 1697 return (ENOENT); 1698 #ifdef MAC 1699 SOCK_LOCK(so); 1700 error = mac_check_socket_visible(cred, so); 1701 SOCK_UNLOCK(so); 1702 if (error) 1703 return (error); 1704 #endif 1705 if (cr_seeotheruids(cred, so->so_cred)) 1706 return (ENOENT); 1707 if (cr_seeothergids(cred, so->so_cred)) 1708 return (ENOENT); 1709 1710 return (0); 1711 } 1712 1713 /* 1714 * Allocate a zeroed cred structure. 1715 * MPSAFE 1716 */ 1717 struct ucred * 1718 crget(void) 1719 { 1720 register struct ucred *cr; 1721 1722 MALLOC(cr, struct ucred *, sizeof(*cr), M_CRED, M_WAITOK | M_ZERO); 1723 cr->cr_ref = 1; 1724 cr->cr_mtxp = mtx_pool_find(mtxpool_sleep, cr); 1725 #ifdef MAC 1726 mac_init_cred(cr); 1727 #endif 1728 return (cr); 1729 } 1730 1731 /* 1732 * Claim another reference to a ucred structure. 1733 * MPSAFE 1734 */ 1735 struct ucred * 1736 crhold(struct ucred *cr) 1737 { 1738 1739 mtx_lock(cr->cr_mtxp); 1740 cr->cr_ref++; 1741 mtx_unlock(cr->cr_mtxp); 1742 return (cr); 1743 } 1744 1745 /* 1746 * Free a cred structure. 1747 * Throws away space when ref count gets to 0. 1748 * MPSAFE 1749 */ 1750 void 1751 crfree(struct ucred *cr) 1752 { 1753 struct mtx *mtxp = cr->cr_mtxp; 1754 1755 mtx_lock(mtxp); 1756 KASSERT(cr->cr_ref > 0, ("bad ucred refcount: %d", cr->cr_ref)); 1757 if (--cr->cr_ref == 0) { 1758 mtx_unlock(mtxp); 1759 /* 1760 * Some callers of crget(), such as nfs_statfs(), 1761 * allocate a temporary credential, but don't 1762 * allocate a uidinfo structure. 1763 */ 1764 if (cr->cr_uidinfo != NULL) 1765 uifree(cr->cr_uidinfo); 1766 if (cr->cr_ruidinfo != NULL) 1767 uifree(cr->cr_ruidinfo); 1768 /* 1769 * Free a prison, if any. 1770 */ 1771 if (jailed(cr)) 1772 prison_free(cr->cr_prison); 1773 #ifdef MAC 1774 mac_destroy_cred(cr); 1775 #endif 1776 FREE(cr, M_CRED); 1777 } else { 1778 mtx_unlock(mtxp); 1779 } 1780 } 1781 1782 /* 1783 * Check to see if this ucred is shared. 1784 * MPSAFE 1785 */ 1786 int 1787 crshared(struct ucred *cr) 1788 { 1789 int shared; 1790 1791 mtx_lock(cr->cr_mtxp); 1792 shared = (cr->cr_ref > 1); 1793 mtx_unlock(cr->cr_mtxp); 1794 return (shared); 1795 } 1796 1797 /* 1798 * Copy a ucred's contents from a template. Does not block. 1799 * MPSAFE 1800 */ 1801 void 1802 crcopy(struct ucred *dest, struct ucred *src) 1803 { 1804 1805 KASSERT(crshared(dest) == 0, ("crcopy of shared ucred")); 1806 bcopy(&src->cr_startcopy, &dest->cr_startcopy, 1807 (unsigned)((caddr_t)&src->cr_endcopy - 1808 (caddr_t)&src->cr_startcopy)); 1809 uihold(dest->cr_uidinfo); 1810 uihold(dest->cr_ruidinfo); 1811 if (jailed(dest)) 1812 prison_hold(dest->cr_prison); 1813 #ifdef MAC 1814 mac_copy_cred(src, dest); 1815 #endif 1816 } 1817 1818 /* 1819 * Dup cred struct to a new held one. 1820 * MPSAFE 1821 */ 1822 struct ucred * 1823 crdup(struct ucred *cr) 1824 { 1825 struct ucred *newcr; 1826 1827 newcr = crget(); 1828 crcopy(newcr, cr); 1829 return (newcr); 1830 } 1831 1832 /* 1833 * Fill in a struct xucred based on a struct ucred. 1834 * MPSAFE 1835 */ 1836 void 1837 cru2x(struct ucred *cr, struct xucred *xcr) 1838 { 1839 1840 bzero(xcr, sizeof(*xcr)); 1841 xcr->cr_version = XUCRED_VERSION; 1842 xcr->cr_uid = cr->cr_uid; 1843 xcr->cr_ngroups = cr->cr_ngroups; 1844 bcopy(cr->cr_groups, xcr->cr_groups, sizeof(cr->cr_groups)); 1845 } 1846 1847 /* 1848 * small routine to swap a thread's current ucred for the correct one 1849 * taken from the process. 1850 * MPSAFE 1851 */ 1852 void 1853 cred_update_thread(struct thread *td) 1854 { 1855 struct proc *p; 1856 struct ucred *cred; 1857 1858 p = td->td_proc; 1859 cred = td->td_ucred; 1860 PROC_LOCK(p); 1861 td->td_ucred = crhold(p->p_ucred); 1862 PROC_UNLOCK(p); 1863 if (cred != NULL) 1864 crfree(cred); 1865 } 1866 1867 /* 1868 * Get login name, if available. 1869 */ 1870 #ifndef _SYS_SYSPROTO_H_ 1871 struct getlogin_args { 1872 char *namebuf; 1873 u_int namelen; 1874 }; 1875 #endif 1876 /* 1877 * MPSAFE 1878 */ 1879 /* ARGSUSED */ 1880 int 1881 getlogin(struct thread *td, struct getlogin_args *uap) 1882 { 1883 int error; 1884 char login[MAXLOGNAME]; 1885 struct proc *p = td->td_proc; 1886 1887 if (uap->namelen > MAXLOGNAME) 1888 uap->namelen = MAXLOGNAME; 1889 PROC_LOCK(p); 1890 SESS_LOCK(p->p_session); 1891 bcopy(p->p_session->s_login, login, uap->namelen); 1892 SESS_UNLOCK(p->p_session); 1893 PROC_UNLOCK(p); 1894 error = copyout(login, uap->namebuf, uap->namelen); 1895 return(error); 1896 } 1897 1898 /* 1899 * Set login name. 1900 */ 1901 #ifndef _SYS_SYSPROTO_H_ 1902 struct setlogin_args { 1903 char *namebuf; 1904 }; 1905 #endif 1906 /* 1907 * MPSAFE 1908 */ 1909 /* ARGSUSED */ 1910 int 1911 setlogin(struct thread *td, struct setlogin_args *uap) 1912 { 1913 struct proc *p = td->td_proc; 1914 int error; 1915 char logintmp[MAXLOGNAME]; 1916 1917 error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL); 1918 if (error) 1919 return (error); 1920 error = copyinstr(uap->namebuf, logintmp, sizeof(logintmp), NULL); 1921 if (error == ENAMETOOLONG) 1922 error = EINVAL; 1923 else if (!error) { 1924 PROC_LOCK(p); 1925 SESS_LOCK(p->p_session); 1926 (void) memcpy(p->p_session->s_login, logintmp, 1927 sizeof(logintmp)); 1928 SESS_UNLOCK(p->p_session); 1929 PROC_UNLOCK(p); 1930 } 1931 return (error); 1932 } 1933 1934 void 1935 setsugid(struct proc *p) 1936 { 1937 1938 PROC_LOCK_ASSERT(p, MA_OWNED); 1939 p->p_flag |= P_SUGID; 1940 if (!(p->p_pfsflags & PF_ISUGID)) 1941 p->p_stops = 0; 1942 } 1943 1944 /*- 1945 * Change a process's effective uid. 1946 * Side effects: newcred->cr_uid and newcred->cr_uidinfo will be modified. 1947 * References: newcred must be an exclusive credential reference for the 1948 * duration of the call. 1949 */ 1950 void 1951 change_euid(struct ucred *newcred, struct uidinfo *euip) 1952 { 1953 1954 newcred->cr_uid = euip->ui_uid; 1955 uihold(euip); 1956 uifree(newcred->cr_uidinfo); 1957 newcred->cr_uidinfo = euip; 1958 } 1959 1960 /*- 1961 * Change a process's effective gid. 1962 * Side effects: newcred->cr_gid will be modified. 1963 * References: newcred must be an exclusive credential reference for the 1964 * duration of the call. 1965 */ 1966 void 1967 change_egid(struct ucred *newcred, gid_t egid) 1968 { 1969 1970 newcred->cr_groups[0] = egid; 1971 } 1972 1973 /*- 1974 * Change a process's real uid. 1975 * Side effects: newcred->cr_ruid will be updated, newcred->cr_ruidinfo 1976 * will be updated, and the old and new cr_ruidinfo proc 1977 * counts will be updated. 1978 * References: newcred must be an exclusive credential reference for the 1979 * duration of the call. 1980 */ 1981 void 1982 change_ruid(struct ucred *newcred, struct uidinfo *ruip) 1983 { 1984 1985 (void)chgproccnt(newcred->cr_ruidinfo, -1, 0); 1986 newcred->cr_ruid = ruip->ui_uid; 1987 uihold(ruip); 1988 uifree(newcred->cr_ruidinfo); 1989 newcred->cr_ruidinfo = ruip; 1990 (void)chgproccnt(newcred->cr_ruidinfo, 1, 0); 1991 } 1992 1993 /*- 1994 * Change a process's real gid. 1995 * Side effects: newcred->cr_rgid will be updated. 1996 * References: newcred must be an exclusive credential reference for the 1997 * duration of the call. 1998 */ 1999 void 2000 change_rgid(struct ucred *newcred, gid_t rgid) 2001 { 2002 2003 newcred->cr_rgid = rgid; 2004 } 2005 2006 /*- 2007 * Change a process's saved uid. 2008 * Side effects: newcred->cr_svuid will be updated. 2009 * References: newcred must be an exclusive credential reference for the 2010 * duration of the call. 2011 */ 2012 void 2013 change_svuid(struct ucred *newcred, uid_t svuid) 2014 { 2015 2016 newcred->cr_svuid = svuid; 2017 } 2018 2019 /*- 2020 * Change a process's saved gid. 2021 * Side effects: newcred->cr_svgid will be updated. 2022 * References: newcred must be an exclusive credential reference for the 2023 * duration of the call. 2024 */ 2025 void 2026 change_svgid(struct ucred *newcred, gid_t svgid) 2027 { 2028 2029 newcred->cr_svgid = svgid; 2030 }
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